Question 1

In a signal transduction pathway,the signal activates a(n)

Accepted Answer

A)  paracrine molecule. 
B)  responder. 
C)  receptor. 
D)  hormone. 
E)  effector molecule. 
A)  paracrine molecule. 
B)  responder. 
C)  receptor. 
D)  hormone. 
E)  effector molecule.

Question 2

Receptor-mediated endocytosis is the primary mechanism for import of

Accepted Answer

A)  clathrin. 
B)  all macromolecules. 
C)  ions. 
D)  cholesterol. 
E)  integral membrane proteins. 
A)  clathrin. 
B)  all macromolecules. 
C)  ions. 
D)  cholesterol. 
E)  integral membrane proteins.

Question 3

Active transport usually moves molecules

Accepted Answer

A)  in the same direction as diffusion moves them. 
B)  in a direction opposite to the one in which diffusion moves them. 
C)  in a direction that tends to bring about equilibrium. 
D)  from a solution with a lower pH toward one with a higher pH. 
E)  from inside to outside the cell. 
A)  in the same direction as diffusion moves them. 
B)  in a direction opposite to the one in which diffusion moves them. 
C)  in a direction that tends to bring about equilibrium. 
D)  from a solution with a lower pH toward one with a higher pH. 
E)  from inside to outside the cell.

Question 4

If a G protein were unable to release its bound nucleotide but could hydrolyze it,signal transduction would

Accepted Answer

A)  cease. 
B)  be continuous. 
C)  be unaffected. 
D)  be constantly switching on and off. 
E)  be unpredictable. 
A)  cease. 
B)  be continuous. 
C)  be unaffected. 
D)  be constantly switching on and off. 
E)  be unpredictable.

Question 5

Which statement about G proteins is true?

Accepted Answer

A)  G proteins contain only one important binding site. 
B)  When a G protein binds to an activated receptor protein,ADP is exchanged for ATP. 
C)  G protein-linked receptors are transmembrane proteins. 
D)  G proteins usually float free in the cytoplasm. 
E)  G proteins signal only the cell from which they are secreted. 
A)  G proteins contain only one important binding site. 
B)  When a G protein binds to an activated receptor protein,ADP is exchanged for ATP. 
C)  G protein-linked receptors are transmembrane proteins. 
D)  G proteins usually float free in the cytoplasm. 
E)  G proteins signal only the cell from which they are secreted.

Question 6

In hibernating animals during the winter,

Accepted Answer

A)  signal transduction pathways cease. 
B)  membrane lipid composition changes: saturated fatty acids are replaced with unsaturated fatty acids. 
C)  membranes toughen as more saturated fatty acids accumulate in them. 
D)  there are no changes in lipid composition. 
E)  integral proteins shrink as temperatures fall. 
A)  signal transduction pathways cease. 
B)  membrane lipid composition changes: saturated fatty acids are replaced with unsaturated fatty acids. 
C)  membranes toughen as more saturated fatty acids accumulate in them. 
D)  there are no changes in lipid composition. 
E)  integral proteins shrink as temperatures fall.

Question 7

If aquaporins are injected into the membranes of epithelial cells that line blood vessels,

Accepted Answer

A)  the flow of Na+ through aquaporins will increase. 
B)  the intracellular concentration of K+ will increase. 
C)  carrier proteins will bind glucose and enter the bloodstream. 
D)  the membranes will become more permeable to water. 
E)  the electrical properties of the cells will be altered. 
A)  the flow of Na+ through aquaporins will increase. 
B)  the intracellular concentration of K+ will increase. 
C)  carrier proteins will bind glucose and enter the bloodstream. 
D)  the membranes will become more permeable to water. 
E)  the electrical properties of the cells will be altered.

Question 8

After the GTP-bound subunit of the G protein separates from the rest of the G protein,it travels until it encounters

Accepted Answer

A)  an activator. 
B)  a receptor. 
C)  an effector protein. 
D)  a protein kinase. 
E)  another G protein. 
A)  an activator. 
B)  a receptor. 
C)  an effector protein. 
D)  a protein kinase. 
E)  another G protein.

Question 9

Which of the following is not involved in secondary active transport?

Accepted Answer

A)  The direct use of ATP 
B)  Coupling to another transport system 
C)  Use of an existing concentration gradient 
D)  The plasma membrane 
E)  The ability to concentrate the transported molecule 
A)  The direct use of ATP 
B)  Coupling to another transport system 
C)  Use of an existing concentration gradient 
D)  The plasma membrane 
E)  The ability to concentrate the transported molecule

Question 10

Which statement about cyclic AMP is false?

Accepted Answer

A)  It is formed from ATP. 
B)  In some circumstances it can bind to a protein kinase in the cytoplasm. 
C)  The enzyme adenylyl cyclase catalyzes its formation from ATP. 
D)  It is a second messenger. 
E)  It has enzymatic activity. 
A)  It is formed from ATP. 
B)  In some circumstances it can bind to a protein kinase in the cytoplasm. 
C)  The enzyme adenylyl cyclase catalyzes its formation from ATP. 
D)  It is a second messenger. 
E)  It has enzymatic activity.

Question 11

The molecular structure of caffeine mimics the molecular structure of

Accepted Answer

A)  paracrine. 
B)  aspirin. 
C)  adenosine. 
D)  autocrine. 
E)  phosphorine. 
A)  paracrine. 
B)  aspirin. 
C)  adenosine. 
D)  autocrine. 
E)  phosphorine.

Question 12

Which statement about cholesterol molecules is true?

Accepted Answer

A)  They help hold a membrane together. 
B)  They alter the fluidity of the membrane. 
C)  They attach to carbohydrates. 
D)  They disrupt membrane function. 
E)  They transport ions across membranes. 
A)  They help hold a membrane together. 
B)  They alter the fluidity of the membrane. 
C)  They attach to carbohydrates. 
D)  They disrupt membrane function. 
E)  They transport ions across membranes.

Question 13

For a G protein to play its part in moving events forward in a signal pathway,

Accepted Answer

A)  GDP must be released,and a GTP must occupy the nucleotide-binding site. 
B)  GTP must be released,and a GDP must occupy the nucleotide-binding site. 
C)  cGMP must occupy the otherwise empty nucleotide-binding site. 
D)  cGMP must leave the otherwise occupied nucleotide-binding site. 
E)  it must be linked to a specific intracellular receptor. 
A)  GDP must be released,and a GTP must occupy the nucleotide-binding site. 
B)  GTP must be released,and a GDP must occupy the nucleotide-binding site. 
C)  cGMP must occupy the otherwise empty nucleotide-binding site. 
D)  cGMP must leave the otherwise occupied nucleotide-binding site. 
E)  it must be linked to a specific intracellular receptor.

Question 14

To respond to a signal,a cell must have a(n)_______ molecule that can detect the signal.

Accepted Answer

A)  paracrine 
B)  receptor 
C)  autocrine 
D)  responder 
E)  All of the above 
A)  paracrine 
B)  receptor 
C)  autocrine 
D)  responder 
E)  All of the above

Question 15

Signal ligands can be divided into two groups according to the location of their receptors.Which of the following are the two classes of receptors?

Accepted Answer

A)  Plasma membrane and ion channel 
B)  Plasma membrane and protein kinase 
C)  Ion channel and cytoplasmic 
D)  G protein-linked and protein kinase 
E)  Membrane and intracellular 
A)  Plasma membrane and ion channel 
B)  Plasma membrane and protein kinase 
C)  Ion channel and cytoplasmic 
D)  G protein-linked and protein kinase 
E)  Membrane and intracellular

Question 16

The signals that bind to receptors of the same cell that made them are known as

Accepted Answer

A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  hormones. 
E)  responders. 
A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  hormones. 
E)  responders.

Question 17

Which statement about the insulin receptor is false?

Accepted Answer

A)  It is not an ion channel. 
B)  It is a protein kinase receptor. 
C)  It catalyzes the phosphorylation of insulin-response substrates. 
D)  It is located entirely within the cytoplasm. 
E)  It is not regulated by phosphorylation. 
A)  It is not an ion channel. 
B)  It is a protein kinase receptor. 
C)  It catalyzes the phosphorylation of insulin-response substrates. 
D)  It is located entirely within the cytoplasm. 
E)  It is not regulated by phosphorylation.

Question 18

Which of the following is the driving force for facilitated diffusion?

Accepted Answer

A)  Concentration gradient 
B)  ATP hydrolysis 
C)  ADP hydrolysis 
D)  Phosphorylation 
E)  GTP-GDP exchange 
A)  Concentration gradient 
B)  ATP hydrolysis 
C)  ADP hydrolysis 
D)  Phosphorylation 
E)  GTP-GDP exchange

Question 19

Which statement is false?

Accepted Answer

A)  Cells are bombarded with numerous signals,but they respond to only a few. 
B)  A cell's receptors determine whether or not the cell will respond to a signal. 
C)  Receptor proteins are very specific. 
D)  Protein kinase receptors are a type of cytoplasmic receptor. 
E)  All of the above are true;none is false. 
A)  Cells are bombarded with numerous signals,but they respond to only a few. 
B)  A cell's receptors determine whether or not the cell will respond to a signal. 
C)  Receptor proteins are very specific. 
D)  Protein kinase receptors are a type of cytoplasmic receptor. 
E)  All of the above are true;none is false.

Question 20

Which molecule acts as a second messenger in the cascade by which epinephrine stimulates the activation of the enzyme glycogen phosphorylase?

Accepted Answer

A)  Adenosine 
B)  Caffeine 
C)  Citric acid 
D)  Cyclic AMP 
E)  Adenylyl cyclase 
A)  Adenosine 
B)  Caffeine 
C)  Citric acid 
D)  Cyclic AMP 
E)  Adenylyl cyclase

Exam 5: Cell Membranes and Signaling

In a signal transduction pathway,the signal activates a(n)

Receptor-mediated endocytosis is the primary mechanism for import of

Active transport usually moves molecules

If a G protein were unable to release its bound nucleotide but could hydrolyze it,signal transduction would

Which statement about G proteins is true?

In hibernating animals during the winter,

If aquaporins are injected into the membranes of epithelial cells that line blood vessels,

After the GTP-bound subunit of the G protein separates from the rest of the G protein,it travels until it encounters

Which of the following is not involved in secondary active transport?

Which statement about cyclic AMP is false?

The molecular structure of caffeine mimics the molecular structure of

Which statement about cholesterol molecules is true?

For a G protein to play its part in moving events forward in a signal pathway,

To respond to a signal,a cell must have a(n)_______ molecule that can detect the signal.

Signal ligands can be divided into two groups according to the location of their receptors.Which of the following are the two classes of receptors?

The signals that bind to receptors of the same cell that made them are known as

Which statement about the insulin receptor is false?

Which of the following is the driving force for facilitated diffusion?

Which statement is false?

Which molecule acts as a second messenger in the cascade by which epinephrine stimulates the activation of the enzyme glycogen phosphorylase?

Introduction

The Chemistry and Energy of Life

Nucleic Acids, Proteins, and Enzymes

Cells: the Working Units of Life

Pathways That Harvest and Store Chemical Energy

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

DNA and Its Role in Heredity

From Dna to Protein: Gene Expression

Regulation of Gene Expression

Genomes

Biotechnology

Genes, Development, and Evolution

Processes of Evolution

Reconstructing and Using Phylogenies

Speciation

The History of Life on Earth

Bacteria, Archaea, and Viruses

The Origin and Diversification of Eukaryotes

The Evolution of Plants

The Evolution and Diversity of Fungi

Animal Origins and Diversity

The Plant Body

Plant Nutrition and Transport

Plant Growth and Development

Reproduction of Flowering Plants

Plants in the Environment

Fundamentals of Animal Function

Nutrition and Digestion

Breathing

Circulation

Muscle and Movement

Neurons, Sense Organs, and Nervous Systems

Nervous and Endocrine Control

Water and Salts: Excretion

Animal Reproduction

Animal Development

Immunology: Animal Defense Systems

Animal Behavior

The Distribution of Earths Ecological Systems

Populations

Ecological and Evolutionary Consequences of Interactions Within and Among Species

Ecological Communities

The Global Ecosystem

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